1. Field of the Invention
This invention relates generally to laundry processing and more particularly to an extraction system that processes laundry in discrete batches in a continuous fashion.
2. Brief Description of the Background Art
With the advent of ultra high capacity tunnel washers which are capable of continuously processing enormous quantities of laundry in discrete batches, the need for more advanced systems of extraction for use in conjunction with these washers has grown dramatically. Tunnel washers have a plurality of sections linked by a rotating archimedian screw, so that discrete batches of laundry may be continuously processed through the washer. Currently, membrane presses are used for liquid extraction in conjunction with tunnel washers. Membrane presses have an internal membrane which squeezes the laundry into a compressed state known as a cheese in order to remove the fluid from the washed laundry. Normally, after membrane-type extraction, subsequent drying, for example in a tumble dryer, is required because these extractors are not highly efficient.
Centrifugal extractors with internal drums that rotate at high speed to centrifugally expel the water or other cleaning fluid from the laundry are known to be highly advantageous in terms of energy efficiency and effectiveness of liquid removal. However, centrifugal extractors are not generally believed to be amenable to high capacity or high output continuous processing. Because of the slow speed of operation of centrifugal extractors, current practice requires the use of a plurality of centrifugal extractors to keep up with one high capacity tunnel washer. Moreover centrifugal extractors generally are incapable of accepting and processing discrete laundry batches, other than one at a time. Thus, due to inefficiencies in transferring between the washers and the centrifugal extractors as well as deficiencies in speed of operation and in loading and unloading efficiency, centrifugal extractors have not been found to be satisfactory for use in conjunction with the high capacity tunnel washers.
A significant deficiency in presently known commercial centrifugal extraction systems is that they are prone to developing non-uniform load distributions resulting in load imbalances destructive to the apparatus. In addition after processing in the centrifugal extractor, the laundry is sometimes difficult to remove because it tends to pack along the peripheral surface of the drum. In U.S. Pat. No. 3,945,921 to Toth a system for automatically expelling the laundry after centrifugal extraction is disclosed. After processing, the laundry is raised out of the extractor drum on a reciprocal wall that is still rotating. The laundry is expelled onto a plurality of surrounding conveyors where it is collected for additional processing. Segmented centrifugal extraction drums that divide the laundry into separate portions decreasing the likelihood of developing imbalance problems are known in the art. U.S. Pat. Nos. 3,577,751, 3,570,273, 2,808,153, 2,534,286, and 1,938,146 disclose washing machines or extractors with segmented, rotating drums.
Automatic systems for processing laundry are also known in the art. For example, U.S. Pat. No. 3,844,142 to Miller discloses a hydraulic press extractor which compresses the laundry into a cake. The extractor is used in conjunction with a conveyor system to automatically process laundry received on the conveyor from a washer. In U.S. Pat. No. 4,285,219 issued to Grunewald an apparatus which uses centrifugal extraction and vacuum conveying in conjunction with conventional commercial laundry machines is taught.